We plan to: (a) Continue our studies of the mechanisms of serine hydroxymethylase, serine dehydratase, cis,cis-muconate cycloisomerase, and muconolactone isomerases by steady state and topped flow kinetics methods, cryoenzymology, magnetic resonance techniques, proton uptake and loss experiments and the employment of substituted substrates. (b) Continue our studies of the structures of the active sites of several of the above mentioned enzymes by protein side group modification, the employment of suicide substrates, CD, nmr, and, if suitable crystals can be obtained, X-ray diffraction studies. (c) Determine the absolute stereochemistry of the chemical group replacements in several of the aforementioned reactions. (d) Elucidate the mechanisms of inter- and intramolecular Mannich reactions and the PLP model systems involving dealdolization and dehydrative/deamination reactions.